The present invention relates to an ignition displacement angle control device for a gasoline engine.
The conventional vacuum type ignition displacement angle control device for a gasoline engine is of such a design that timing for ignition is conducted by virtue of a load applied to the gasoline engine, wherein a negative pressure intake port is formed through the wall of a vaporizer and any fluctuation in the degree of the vacuum therein is caused to act on the diaphragm chamber of a distributor. The base plate of the case or the arm of an interrupter is caused to resolve by means of a linking mechanism that is fixed in place on the diaphgram, whereby the ignition timing is changed. The conventional ignition displacement angle control device is so designed that ignition timing is caused to be delayed during the racing of the gasoline engine and at the time of operation thereof under the total load as well, and high level partial vacuum functions on the said diaphragm at the time of operation under the intermediate load, thus causing the ignition time to be advanced.
However, as rigid controls over the exhaust gas have recently been instituted, the prior art method of advancing the ignition time under the intermediate load using a conventional vacuum type ignition displacement angle control device, for example by opening the throttle valve of a vaporizer to some certain degree, has the effect that the ignition time can hardly be advanced to a satisfactory level in some case. Such being the situation, now that the combustion temperature in the engine cylinder is required to be reduced down to as low a level as practicable for the purpose of reducing the quantity of NO.sub.x generated in a gasoline engine, it is desireable that the ignition time be delayed as much as possible in order to meet the requirement.